铝基体超疏水表面结冰结霜特性研究

采用中性电解液,通过电化学加工技术及氟化处理方法制备出铝基体超疏水表面,接触角达160°,滚动角小于5°,并在其上进行了结冰和结霜研究.在不同实验条件下研究超疏水表面的形貌、霜高随时间的变化,并与相同条件下的普通铝表面、吸水性表面进行了对比.结果表明,该超疏水表面经过50多次结霜、除霜后,仍具有很好的超疏水性能,表现出良好的重复性和耐久性;与普通铝表面相比,铝基体超疏水表面具有明显的抗结冰结霜性能,霜晶先出现在四周边缘处并逐渐蔓延到中间,但抑霜能力随着冷表面温度的降低而减小;与吸水性表面相比,超疏水表面在抗结冰结霜的同时能有效抑制表面质量的增加.     

超疏水铝表面的一步法电化学制备及其耐蚀性能研究

金属材料的表面超疏水改性可以显著改善其耐腐蚀性能.为了制备超疏水铝合金表面,结合化学刻蚀与电化学氧化技术,采用一步法在铝表面构筑超疏水结构,研究了其中盐酸含量和氧化时间对铝电极表面结构和性能的影响.采用接触角测试仪表征了铝表面的疏水性能,利用扫描电镜和能谱仪分析了铝表面的微观形貌和化学组成.采用电化学阻抗谱和电化学噪声技术评价了改性铝电极在3.5％NaCl溶液中的耐蚀性能.结果表明:当盐酸浓度为0.015 mol/L,电压为2 V,氧化时间为20 min时,可在纯铝上制备得到接触角为155.8°、滚动角为3.1°的超疏水表面.电化学阻抗测试结果表明,电荷转移电阻由121 Ω·cm2增大至1 941 Ω·cm2,超疏水铝表面的保护效率高达93.8％.电化学噪声测试表明,铝电极表面的超疏水改性能够显著地减弱其在3.5％NaCl溶液中的局部腐蚀强度.     

铝基体超疏水表面的抗结冰结霜效果分析

增加接触角是提高表面抗结冰结霜能力的重要方法.借助电化学加工和氟化处理获得铝基体超疏水表面,该表面具有二元微纳米复合结构,干燥时水滴在其上的接触角为160°,滚动角小于5°,处于Cassie-Baxter状态.在自制的半导体制冷台上,观测冷表面温度为-5.2 ℃时,铝基体超疏水表面的结霜过程,并将其与普通铝表面进行了对比,发现铝基体超疏水表面的四周边缘处先出现霜晶并逐渐蔓延到整个表面,与普通铝表面相比具有显著的抗结冰结霜性能.最后对铝基体超疏水表面的边缘效应和抗结冰结霜机理进行了分析.     

铝基表面超疏水材料的制备工艺、效果及耐蚀性

超疏水表面在自清洁材料、腐蚀防护及微流体运输等领域有着广阔的应用前景,目前对金属超疏水表面的研究较少,且制备方法较复杂,不能大面积制备。分别采用喷砂、阳极氧化、喷砂-阳极氧化等方法在铝基体表面构造粗糙结构并对其进行修饰,制备了超疏水表面,通过SEM、接触角及滚动角测定、腐蚀速率测定等分析了超疏水表面的微观形貌、疏水性能和耐海水腐蚀性能。结果表明:喷砂-阳极氧化法制备的铝金属表面具有微米-纳米二级结构,经氟化处理后,与水的接触角达158°,滚动角为1.5°,疏水性能良好;超疏水表面材料的腐蚀速率比铝材低1个数量级。     

MB8镁合金超疏水表面的制备和润湿性

通过激光加工在MB8镁合金表面构造具有规则结构的纹理,再制备1H,1H,2H,2H-全氟葵烷基三氯硅烷(FDTS)自组装分子膜,从而构建了MB8镁合金超疏水表面。用扫描电子显微镜和接触角测量仪观察和测量试样表面的形貌和润湿性。结果表明,激光加工在试样表面构造的粗糙结构和低表面能物质FDTS自组装分子膜使该试样具有超疏水性;经激光加工和沉积自组装分子膜后,MB8镁合金试样表面对水的接触角显著增大(达到150°以上)。将MB8镁合金超疏水表面加工成漂浮平台,承载能力的测试结果表明,超疏水平台的漂浮承载能力明显比非超疏水性平台的大,平台的承载能力与接触角的数值成正比。理论计算结果和"气垫"的存在表明,该超疏水表面符合Cassie-Baxter。状态模型,对接触角理论值与测量值的分析表明分级粗糙结构对超疏水表面构建有重要作用。     

超疏水表面结构对结露影响的研究

利用仿生技术制备超疏水表面可以防止或减少金属表面结露结霜,得到了广泛深入地研究。就是利用这一技术采用激光刻蚀和纳米溶液制备超疏水表面分别得到了具有超疏水性能的铝块、硅片。并将这些样品搁置在一定的环境条件下利用高速摄像机观察其表面的抗凝露效果,提出了采用液滴在表面脱落频率和脱落直径来衡量固体表面上的液滴更新频率的快慢,进而衡量固体表面的抗凝效果。通过观察普通铝块与超疏水铝块、不同结构的超疏水硅片之间的表面凝露情况,得出超疏水表面的凝结的水滴与样品的表面接触角大,接触面积较小,以Cassie-Baxter状态悬停在微纳米方柱上,在很小的外力作用下就能离开固体表面,从而达到抗凝露效果。     

疏水性对竖直冷表面上自然对流结霜特性的影响

本文采用控制表面氧化法制备超疏水表面(153. 2°),并对自然对流条件下竖直放置的超疏水表面与裸铜表面进行可视化结霜实验,观察并对比实验初期有液核与无液核生成成霜时疏水性对结霜过程的影响,研究了疏水性对结霜的影响随冷表面温度(-50～-30℃)、空气相对湿度(30%～70%)的变化规律。结果表明,有液核成霜时,超疏水表面具有显著的抑霜效果;无液核成霜时,疏水表面不再具有抑霜效果,反而超疏水表面霜晶生长更为密实;疏水性对无液核成霜过程的影响随空气相对湿度的增大、冷表面温度的降低而减弱;从云物理学与核化理论角度分析了无液核生成时超疏水表面霜晶分布更密的原因,发现实验制备的超疏水表面上凹坑与CuO晶体颗粒为凝华核化提供了有利位置。     

氧化锌超疏水薄膜的制备及其耐久性

为了提高氧化锌(ZnO)纳米疏水膜层在实际应用中的耐久性能,采用水热法在铝基底表面制备出微纳米结构的ZnO超疏水薄膜,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和接触角测量仪对所得ZnO薄膜的成分、微观结构及润湿性能进行分析;利用UMT摩擦磨损试验机对薄膜的摩擦性能和机械疏水耐久度进行研究;并用CHI660E电化学工作站对超疏水试样在海水中的耐腐蚀性能进行测量分析。结果表明:制备的微纳米结构ZnO薄膜具有超疏水性,在未经低表面能物质改性的情况下,对水的静态接触角高达152°,滚动角仅为2°;摩擦磨损测试表明该薄膜在经过2 400磨损周期后仍能保持较高的静态接触角;电化学阻抗谱和Tafel曲线测试表明,该薄膜的确降低了铝在海水中的腐蚀速率,缓蚀率高达93.8%。     

溶胶-凝胶原位生长制备超疏水木材

采用溶胶-凝胶原位生长的方法制备超疏水木材,在木材表面形成一层纳米结构超疏水薄膜,水滴在木材表面接触角达到150.6°。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、傅立叶变换红外光谱仪(FTIR)分别对超疏水木材样品的物相组成、表面形貌及表面化学官能团进行检测,分析表明木材的超疏水性是表面纳米级突起粗糙结构和乙烯基疏水基团共同作用的结果。     

热喷涂锌铝合金超疏水涂层的制备及性能

用电弧喷涂技术在Q235钢板上喷涂锌铝合金涂层,用硬脂酸/乙醇的表面修饰技术在锌铝合金涂层表面构筑了一层超疏水膜。用接触角测量仪(OCA-20),扫描电子显微镜(SEM)和智能型傅立叶红外光谱仪(ATR)等手段表征了涂层修饰前后的润湿性、表面形貌以及化学结构,并用三电极体系电化学工作站(Solartron analytical)对硬脂酸表面修饰前后锌铝涂层进行了阻抗谱和极化测试。结果表明:热喷涂锌铝涂层具有微/纳复合结构,修饰前涂层表现为亲水性,因为金属涂层具有高表面能;经过硬脂酸表面修饰后涂层的静态接触角达到153.2°,滚动角小于10°;红外分析结果表明,锌铝涂层表面由大量的疏水性烃基长链组成,有超疏水作用;腐蚀测试结果表明,修饰处理能明显提高锌铝涂层的防腐蚀性。涂层表面形成的超疏水膜阻碍了界面电化学反应腐蚀产物的脱落与溶解,提高了电荷转移电阻,降低了电流腐蚀密度,从而提高了涂层的防腐蚀性。     

Rapid fabrication of large-area, corrosion-resistant superhydrophobic Mg alloy surfaces

A superhydrophobic magnesium (Mg) alloy surface was successfully fabricated via a facile electrochemical machining process, and subsequently covered with a fluoroalkylsilane (FAS) film. The surface morphologies and chemical compositions were investigated using a scanning electron microscope (SEM) equipped with an energy-dispersive spectroscopy (EDS) and a Fourier-transform infrared spectrophotometer (FTIR). The results show hierarchal rough structures and an FAS film with a low surface energy on the Mg alloy surfaces, which confers good superhydrophobicity with a water contact angle of 165.2° and a water tilting angle of approximately 2°. The processing conditions, such as the processing time and removal rate per unit area at a constant removal mass per unit area, were investigated to determine their effects on the superhydrophobicity. Interestingly, when the removal mass per unit area is constant at approximately 11.10 mg/cm(2), the superhydrophobicity does not change with the removal rate per unit area. Therefore, a superhydrophobic Mg alloy surface can be rapidly fabricated based on this property. A large-area superhydrophobic Mg alloy surface was also fabricated for the first time using a small-area moving cathode. The corrosion resistance and durability of the superhydrophobic surfaces were also examined.     

One-step electrochemical machining of superhydrophobic surfaces on aluminum substrates

A superhydrophobic surface on an aluminum substrate was fabricated by one-step electrochemical machining using the sodium chloride (NaCl) aqueous solution containing fluoroalkylsilane as the electrolyte. The resulting superhydrophobic surfaces showed a static water contact angle of 166° and a tilting angle of about 1°. The morphological features and chemical compositions were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), electron probe micro-analyzer (EPMA), and Fourier-transform infrared spectrometer (FTIR). It shows that the binary micrometer–nanometer-scale rough structures and the low surface energy coating were present on the aluminum surfaces. The resulting surfaces have good properties of anti-adhesion and self-cleaning. The durability of the superhydrophobic surfaces on aluminum substrates was also investigated. This preparation method is advantageous as it does not require acid electrolyte or a separate process to lower the surface energy, uses simple steps, and is environmental friendly and highly efficient.     

Large-area fabrication of superhydrophobic surfaces for practical applications: an overview

This review summarizes the key topics in the field of large-area fabrication of superhydrophobic surfaces, concentrating on substrates that have been used in commercial applications. Practical approaches to superhydrophobic surface construction and hydrophobization are discussed. Applications of superhydrophobic surfaces are described and future trends in superhydrophobic surfaces are predicted.     

Large-area fabrication of superhydrophobic surfaces for practical applications: an overview

Abstract

This review summarizes the key topics in the field of large-area fabrication of superhydrophobic surfaces, concentrating on substrates that have been used in commercial applications. Practical approaches to superhydrophobic surface construction and hydrophobization are discussed. Applications of superhydrophobic surfaces are described and future trends in superhydrophobic surfaces are predicted.     

氧化还原法制备超疏水表面及其防覆冰性能

使用化学氧化还原法制备出疏水性能优异的超疏水表面,使用接触角测量仪、扫描电镜对表面浸润性及形貌进行表征分析。制得的铝基体超疏水表面接触角高达163.31°,滚动角小于5°。探究不同反应时间对表面形貌和浸润性的影响,使用自制的结冰监测系统对制备出的超疏水表面的静态和动态水滴防覆冰性能进行探究,并结合一维传热理论和经典成核理论对实验结果进行分析。结果表明,反应80min时表面疏水效果最好,超疏水表面静态水滴延缓结冰时间约是普通样品的5倍,结冰温度也低了3.3℃,动态水滴撞击表面时,超疏水表面始终无积水和覆冰,表现出优异的静态和动态防覆冰性能。     

Functionalized superhydrophobic coatings with micro-/nanostructured ZnO particles in a sol–gel matrix

Among the methods to create superhydrophobic surfaces by wet chemistry, one of the strategies consists in coating the substrate with a hydrophobic polymer with specific morphology. Such elaborated surfaces are largely developed and can present complex architectures but are generally fragile. Ceramic-based coatings show better durability. In this work, a new route associating inorganic and polymeric parts is used. Surfaces with superhydrophobic properties are prepared with a mixture of zinc oxide (ZnO) particles in a hybrid organic inorganic matrix prepared via sol–gel route. ZnO particles were synthesized by the inorganic polycondensation route and exhibit an appropriate micro-/nanostructure for superhydrophobicity. Sol–gel matrix is obtained by the alkoxide route with aluminum-tri-sec-butoxide (ASB) and (3-glycidoxypropyl)trimethoxysilane (GPTMS). A step of octadecylphosphonic acid (ODP) functionalization on ZnO particles and on film surfaces was employed to considerably improve hydrophobic properties. This new route enables to obtain superhydrophobic coatings that exhibit water contact angles superior to 150°. These coatings show a homogeneous and smooth coverage on aluminum alloy substrate. Results attest the significance of the synergy for superhydrophobic coatings: a micro-/nanostructured surface and an intrinsic hydrophobic property of the material. The durability of the coatings has also been demonstrated with only a slight decrease in hydrophobicity after erosion.     

激光纹理化调控材料表面疏水性能研究进展

超疏水表面由于具有减阻、抗污、防水等独特性能,广泛应用于日常生活、军事、工业等场景,材料表面的微纳结构及化学成分对其超疏水性能有着重要影响。激光纹理化技术由于具有加工分辨率高、加工方式灵活、可加工材料多等优势,可用于制备疏水性能精确可控的表面微纳结构,在制造超疏水表面方面有着广阔的应用前景。首先,介绍了激光纹理化的作用机理,综述了常用的激光纹理化方式,如激光直接写入法、激光干涉图案化法及激光诱导周期性结构法等,并介绍了激光参数对微纳结构的影响。根据表面微纳结构的形貌、周期及尺寸特点对激光纹理化制备的表面分层微纳结构进行了总结归纳,包括覆盖随机纳米结构或激光诱导周期性结构的微沟槽、微网格、微柱及微峰,重点介绍了分层微纳结构的制备方式及微纳结构对疏水性的影响。总结了提高分层微纳结构表面疏水性的后处理方式,包括环境老化、表面化学改性及热处理等,并介绍了后处理方式调控疏水性的作用机理。最后,对采用激光纹理化技术制备超疏水表面的应用前景进行了展望。     

Water-Repellent Approaches for 3-D Printed Internal Passages

In this work, two different manufacturing approaches are presented that create water-repellency (hydrophobicity and super-hydrophobicity) for acrylonitrile butadiene styrene (ABS) structures. In particular, this is the first study to render three-dimensional (3-D) printed ABS surfaces with internal flow paths to be superhydrophobic. The first approach uses standard wet-based chemical processing for surface preparation after which a fluorocarbon layer is deposited by dip coating or with vapor deposition. This first approach creates hydrophobic surfaces with roll-off angles of less than 30°. In the second approach, the ABS structures are dip-coated with a commercial rubber coating solution and subsequently surface-modified by reactive ion etching (RIE) with fluorinated gases to render the samples superhydrophobic, with roll-off angles as low as 6°. In order to further enhance their water-repellency, the dip-coating rubber solution is mixed with polytetrafluoroethylene (PTFE) colloidal dispersions to form a nanocomposite layer prior to the RIE process. The PTFE particles induce surface roughness as well as hydrophobicity. The modified surfaces created by the two approaches are further characterized by scanning electron microscopy and water drainage performance. Water drainage (prevention of water retention) is especially important for high thermal efficiency of 3-D printed heat exchangers. However, water-repellency for ABS is also interesting for a broader range of applications that use this material.     

Micro/nano engineering on stainless steel substrates to produce superhydrophobic surfaces

Creating micro-/nano-scale topography on material surfaces to change their wetting properties has been a subject of much interest in recent years. Wenzel in 1936 and Cassie and Baxter in 1944 proposed that by microscopically increasing the surface roughness of a substrate, it is possible to increase its hydrophobicity. This paper reports the fabrication of micro-textured surfaces and nano-textured surfaces, and the combination of both on stainless steel substrates by sandblasting, thermal evaporation of aluminum, and aluminum-induced crystallization (AIC) of amorphous silicon (a-Si). Meanwhile, fluorinated carbon films were used to change the chemical composition of the surfaces to render the surfaces more hydrophobic. These surface modifications were investigated to create superhydrophobic surfaces on stainless steel substrates. The topography resulting from these surface modifications was analyzed by scanning electron microscopy and surface profilometry. The wetting properties of these surfaces were characterized by water contact angle measurement. The results of this study show that superhydrophobic surfaces can be produced by either micro-scale surface texturing or nano-scale surface texturing, or the combination of both, after fluorinated carbon film deposition.